// Copyright 2016 The Draco Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#ifndef DRACO_COMPRESSION_ATTRIBUTES_ATTRIBUTES_ENCODER_H_
#define DRACO_COMPRESSION_ATTRIBUTES_ATTRIBUTES_ENCODER_H_

#include "draco/attributes/point_attribute.h"
#include "draco/core/encoder_buffer.h"
#include "draco/point_cloud/point_cloud.h"

namespace draco {

class PointCloudEncoder;

// Base class for encoding one or more attributes of a PointCloud (or other
// geometry). This base class provides only the basic interface that is used
// by the PointCloudEncoder.
class AttributesEncoder {
  public:
    AttributesEncoder();
    // Constructs an attribute encoder associated with a given point attribute.
    explicit AttributesEncoder(int point_attrib_id);
    virtual ~AttributesEncoder() = default;

    // Called after all attribute encoders are created. It can be used to perform
    // any custom initialization, including setting up attribute dependencies.
    // Note: no data should be encoded in this function, because the decoder may
    // process encoders in a different order from the decoder.
    virtual bool Initialize(PointCloudEncoder *encoder, const PointCloud *pc);

    // Encodes data needed by the target attribute decoder.
    virtual bool EncodeAttributesEncoderData(EncoderBuffer *out_buffer);

    // Returns a unique identifier of the given encoder type, that is used during
    // decoding to construct the corresponding attribute decoder.
    virtual uint8_t GetUniqueId() const = 0;

    // Encode attribute data to the target buffer.
    virtual bool EncodeAttributes(EncoderBuffer *out_buffer) {
        if (!TransformAttributesToPortableFormat())
            return false;
        if (!EncodePortableAttributes(out_buffer))
            return false;
        // Encode data needed by portable transforms after the attribute is encoded.
        // This corresponds to the order in which the data is going to be decoded by
        // the decoder.
        if (!EncodeDataNeededByPortableTransforms(out_buffer))
            return false;
        return true;
    }

    // Returns the number of attributes that need to be encoded before the
    // specified attribute is encoded.
    // Note that the attribute is specified by its point attribute id.
    virtual int NumParentAttributes(int32_t /* point_attribute_id */) const {
        return 0;
    }

    virtual int GetParentAttributeId(int32_t /* point_attribute_id */,
                                     int32_t /* parent_i */) const {
        return -1;
    }

    // Marks a given attribute as a parent of another attribute.
    virtual bool MarkParentAttribute(int32_t /* point_attribute_id */) {
        return false;
    }

    // Returns an attribute containing data processed by the attribute transform.
    // (see TransformToPortableFormat() method). This data is guaranteed to be
    // encoded losslessly and it can be safely used for predictors.
    virtual const PointAttribute *GetPortableAttribute(
        int32_t /* point_attribute_id */) {
        return nullptr;
    }

    void AddAttributeId(int32_t id) {
        point_attribute_ids_.push_back(id);
        if (id >= static_cast<int32_t>(point_attribute_to_local_id_map_.size()))
            point_attribute_to_local_id_map_.resize(id + 1, -1);
        point_attribute_to_local_id_map_[id] = point_attribute_ids_.size() - 1;
    }

    // Sets new attribute point ids (replacing the existing ones).
    void SetAttributeIds(const std::vector<int32_t> &point_attribute_ids) {
        point_attribute_ids_.clear();
        point_attribute_to_local_id_map_.clear();
        for (int32_t att_id : point_attribute_ids) {
            AddAttributeId(att_id);
        }
    }

    int32_t GetAttributeId(int i) const {
        return point_attribute_ids_[i];
    }
    uint32_t num_attributes() const {
        return point_attribute_ids_.size();
    }
    PointCloudEncoder *encoder() const {
        return point_cloud_encoder_;
    }

  protected:
    // Transforms the input attribute data into a form that should be losslessly
    // encoded (transform itself can be lossy).
    virtual bool TransformAttributesToPortableFormat() {
        return true;
    }

    // Losslessly encodes data of all portable attributes.
    // Precondition: All attributes must have been transformed into portable
    // format at this point (see TransformAttributesToPortableFormat() method).
    virtual bool EncodePortableAttributes(EncoderBuffer *out_buffer) = 0;

    // Encodes any data needed to revert the transform to portable format for each
    // attribute (e.g. data needed for dequantization of quantized values).
    virtual bool EncodeDataNeededByPortableTransforms(EncoderBuffer *out_buffer) {
        return true;
    }

    int32_t GetLocalIdForPointAttribute(int32_t point_attribute_id) const {
        const int id_map_size = point_attribute_to_local_id_map_.size();
        if (point_attribute_id >= id_map_size)
            return -1;
        return point_attribute_to_local_id_map_[point_attribute_id];
    }

  private:
    // List of attribute ids that need to be encoded with this encoder.
    std::vector<int32_t> point_attribute_ids_;

    // Map between point attribute id and the local id (i.e., the inverse of the
    // |point_attribute_ids_|.
    std::vector<int32_t> point_attribute_to_local_id_map_;

    PointCloudEncoder *point_cloud_encoder_;
    const PointCloud *point_cloud_;
};

}  // namespace draco

#endif  // DRACO_COMPRESSION_ATTRIBUTES_ATTRIBUTES_ENCODER_H_
